Oxygen vacancies in nanostructured hetero-interfacial oxides: a review

Dharanya, C.; Dharmalingam, Gnanaprakash

doi:10.1007/s11051-022-05440-4

Cited by 7 publications

(5 citation statements)

References 359 publications

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“…The defect reaction for Reaction (3) during reduction process can be written as:

\begin{equation}{{\mathrm{O}}}_{\mathrm{o}}\ \to \ \frac{1}{2}{{\mathrm{O}}}_2\left( {\mathrm{g}} \right) + {{\mathrm{V}}}_{\mathrm{o}}\ \end{equation}

where

{{\mathrm{O}}}_{\mathrm{o}}

and

{{\mathrm{V}}}_{\mathrm{o}}

are occupied lattice oxygen site and vacant oxygen lattice site. From observing Reactions (3) and (4) one can say that the vacant oxygen lattice site holds two electrons in the trapped state generated during the reduction process 41,42 . The oxygen vacancies generated in the reducing atmosphere are uncharged due to the electrons being trapped.…”

Section: Resultsmentioning

confidence: 99%

“…From observing Reactions (3) and ( 4) one can say that the vacant oxygen lattice site holds two electrons in the trapped state generated during the reduction process. 41,42 The oxygen vacancies generated in the reducing atmosphere are uncharged due to the electrons being trapped. In contrast, the oxygen vacancies generated via doping are negatively charged due to the sub-stitution of dopant ions for zirconium ions.…”

Section: Paramagnetic Defects In 10 Mol% Cao-doped Zirconiamentioning

confidence: 99%

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Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Reddy,

Lakshya,

Chowdhury

2024

J Am Ceram Soc.

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A vacuum environment is usually preferred for reducing the dwell time and sintering temperature for doped zirconia ceramics. However, for the present work with 10 mol.% CaO‐doped ZrO2 (10CaSZ) ceramics, both hot‐pressing and vacuum sintering techniques yielded ceramics with open pores (ρ ∼ 93%) and significant amounts of the deleterious monoclinic phase (50%). This is in stark contrast with the conventionally sintered highly dense (>99%) 10CaSZ ceramics, where only tetragonal and cubic phases were noted. Probing via electron paramagnetic resonance (EPR) depicted the trapping of oxygen vacancies by vacancies generated in vacuum at high temperature. A possible change in the local coordination (of ions) and the subsequent chemical environment was confirmed by the observed asymmetric signal shape and broader linewidth of the EPR signals. Potential loss of oxygen and deviation from stoichiometry (for dopant) was confirmed via EPR analysis along with the support of energy dispersive spectra analysis. Despite no noticeable shift in the XRD pattern for Ca2+ depletion, the observed compositional gradient differences in the calcium elemental mapping suggested dopant segregation at the grain boundaries. The conclusions from the present work point toward specificity of a given materials system for its beneficial densification under hot pressing or vacuum sintering.

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“…The defect reaction for Reaction (3) during reduction process can be written as:

\begin{equation}{{\mathrm{O}}}_{\mathrm{o}}\ \to \ \frac{1}{2}{{\mathrm{O}}}_2\left( {\mathrm{g}} \right) + {{\mathrm{V}}}_{\mathrm{o}}\ \end{equation}

where

{{\mathrm{O}}}_{\mathrm{o}}

and

{{\mathrm{V}}}_{\mathrm{o}}

Section: Resultsmentioning

confidence: 99%

Section: Paramagnetic Defects In 10 Mol% Cao-doped Zirconiamentioning

confidence: 99%

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Reddy,

Lakshya,

Chowdhury

2024

J Am Ceram Soc.

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“…Improvement in the FF of photovoltaic devices is generally due to the decreased surface and interface recombination [50]. Moreover, creating higher oxygen vacancies enriches the electrical conductivity of TiO 2 layers, which alternatively helps improve the photovoltaic device parameter of heterojunction devices [10,51,52]. Thus, due to the combined effect of work function tuning, higher oxygen vacancies, higher effective carrier mobility, reduced trap states, and better diode quality, the PCE of T3 devices has been higher [53].…”

Section: Resultsmentioning

confidence: 99%

Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO₂ contact deposition temperature

Pandey,

Kumar,

Mondal

et al. 2024

J. Phys. D: Appl. Phys.

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Carrier selective contacts are a primary requirement for fabricating silicon heterojunction solar cells (SHSCs). TiO2 is a prominent carrier selective contact in SHSCs owing to its excellent optoelectronic features such as suitable band offset, work function, and cost-effectiveness. Herein, we fabricated simple SHSCs in an Al/TiO2/p-Si/Ti/Au device configuration. Ultrathin 3 nm TiO2 layers were deposited onto a p-type silicon substrate using the atomic layer deposition method. The deposition temperature of TiO2 layers varied from 100 °C to 250 °C. X-ray photoelectron spectroscopic studies suggest that deposition temperature highly affects the chemical states of TiO2 and reduces the formation of defective state densities at the Fermi energy. The optical band gap values of TiO2 layers are also altered from 3.13 eV to 3.27 eV when the deposition temperature increases. The work function tuning from -5.13 eV to -4.83 eV has also been observed in TiO2 layers, suggesting the variation in Fermi level tuning, which arises due to changes in carrier concentrations at higher temperatures. Several device parameters, such as ideality factor, trap density, reverse saturation current density, barrier height, etc., have been quantified to comprehend the effects of deposition temperature on photovoltaic device performance. The results suggest that the deposition temperature significantly influences the charge transport and device performance. At an optimum temperature, a significant reduction in charge carrier recombination and trap state density has been observed, which helps to improve power conversion efficiency.

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“…Metal oxide nanostructures are suitable for PT applications because of physiochemical stability and increased availability, in addition to prospects of self-doping through the creation of oxygen vacancies. Specifically, certain oxygen-deficient nonstoichiometric metal oxides [186] such as WO 3−x , MoO 3−x and TiO x with a strong absorption across the UV-NIR range with good thermal stability are being researched on increasingly. For example, titanium oxide, with a bandgap energy of 3 eV in the far UV, can be tailored for absorption in the visible region by doping with other transition metals with high efficacy for PT applications [34,[187][188][189].…”

Section: Doped Metal-oxide Plasmonic Nanomaterialsmentioning

confidence: 99%

Plasmonic nanotechnology for photothermal applications – an evaluation

Indhu¹,

Keerthana²,

Dharmalingam³

2023

Beilstein J. Nanotechnol.

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The application of plasmonic nanoparticles is motivated by the phenomenon of surface plasmon resonance. Owing to the tunability of optothermal properties and enhanced stability, these nanostructures show a wide range of applications in optical sensors, steam generation, water desalination, thermal energy storage, and biomedical applications such as photothermal (PT) therapy. The PT effect, that is, the conversion of absorbed light to heat by these particles, has led to thriving research regarding the utilization of plasmonic nanoparticles for a myriad of applications. The design of conventional nanomaterials for PT conversion has focussed predominantly on the manipulation of photon absorption through bandgap engineering, doping, incorporation, and modification of suitable matrix materials. Plasmonic nanomaterials offer an alternative and attractive approach in this regard, through the flexibility in the excitation of surface plasmons. Specific advantages are the considerable improved bandwidth of the absorption, a higher efficiency of photon absorption, facile tuning, as well as flexibility in the synthesis of plasmonic nanomaterials. This review of plasmonic PT (PPT) research begins with a theoretical discussion on the plasmonic properties of nanoparticles by means of the quasi-static approximation, Mie theory, Gans theory, generic simulations on common plasmonic material morphologies, and the evaluation processes of PT performance. Further, a variety of nanomaterials and material classes that have potential for PPT conversion are elucidated, such as plasmonic metals, bimetals, and metal–metal oxide nanocomposites. A detailed investigation of the essential, but often ignored, concept of thermal, chemical, and aggregation stability of nanoparticles is another part of this review. The challenges that remain, as well as prospective directions and chemistries, regarding nanomaterials for PT conversion are pondered on in the final section of the article, taking into account the specific requirements from different applications.

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Oxygen vacancies in nanostructured hetero-interfacial oxides: a review

Cited by 7 publications

References 359 publications

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO₂ contact deposition temperature

Plasmonic nanotechnology for photothermal applications – an evaluation

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Oxygen vacancies in nanostructured hetero-interfacial oxides: a review

Cited by 7 publications

References 359 publications

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO2 contact deposition temperature

Plasmonic nanotechnology for photothermal applications – an evaluation

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Product

Resources

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Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO₂ contact deposition temperature